The present invention relates to orthodontic pliers, and more particularly, to apparatus and method for bending the distal end of orthodontic arch wires.
Stabilization of orthodontic arch wires against anteroposterior slippage and the protection of oral tissues from puncture type injuries are an important consideration in the .installation of any orthodontic appliance. Conventionally, such objectives are accomplished by adding either welded stops, omega loops or helices to the design of the arch wires so that they may be tied back to molar brackets. It is well known that adding such an essential modification to arch wires requires technical precision and consumes extra clinical and laboratory time. Since the reduction of chain side time has become a driving force for many recent innovations in orthodontic techniques and the appliance industry, most orthodontists began to use distal-end bending as a faster, easier and effective alternative to the conventional tie back techniques. Howe pliers, or tie-back pliers, have been used successfully to bend distal ends of the preformed arch wires as they project from bracket tubes of cemented molar bands.
With the use of bondable molar brackets and, more recently, highly flexible wires, the conventional pliers of the type described above for bending distal ends of flexible arch wires projecting out of bondable molar brackets has been found to be ineffective. The use of conventional pliers often leads to debonding of those brackets and subsequently to failure of the bending procedure. The time required to rebond molar brackets negates any time saving from bending distal ends.
Some reasons for the debonding of molar brackets with the use of currently available pliers include the insufficient angularion of the pliers' jaws to allow comfortable and effective grip of the posteriorly projected distal ends. This is due to the limited accessibility of distal ends far back in the buccal vestibule area. Additionally, poor visibility in that area may result in clumsy or accidental squeezing of the bracket that often leads to the bracket debonding. In addition, the necessary over-bending of distal ends of the highly flexible wires renders this bending procedure difficult for the operator and annoying to the patient. Over-bending of the short distal ends of the arch wires against the distal edge of the bonded bracket tube acting as a fulcrum, creates a dislodging shearing torque, acting on the bracket and leading to its debonding.
As a result of the inavailability of precise pliers, a prolonged, rather than shortened time is often needed to untie and remove the arch wire and rebond the displaced bracket. In order to reliably and efficiently utilize the orthodontic procedure of distal end bending employing highly flexible wires and bondable molar brackets, these problems must be overcome.